1. Field of Invention
The invention relates to an ink-jet head and, more particularly, to an ink-jet head having a cavity plate including a clad plate. The invention also relates to a method of manufacturing such an ink-jet head.
2. Description of Related Art
An ink-jet printer having an ink-jet head is known as a recording device that records images on a recording medium, such as a sheet of paper. As shown in FIG. 13, an ink-jet head 150 of such an ink-jet printer includes a piezoelectric actuator plate 155 that extends and contracts by a drive voltage generated in a driving circuit (not shown), a cavity plate 156 formed with ink passages, and a nozzle plate 157 formed with ink ejecting nozzles 158 and made of synthetic resin, such as polyimide. The actuator plate 155, cavity plate 156, and nozzle plate 157 are vertically stacked so as to be placed at the top, in the middle, and at the bottom, respectively. Each plate 155–157 is a thin plate. The cavity plate 156 is formed by vertically stacking first, second, and third metal layers 156a–156c. Pressure chambers 165 are formed in the first layer 156a by etching so as to store ink therein. Ink is ejected from a selected pressure chamber 165 by the action of the actuator plate 155. A manifold 169 is formed in the third layer 156c by etching so as to supply ink to the pressure chambers 165. Communicating holes 167 are formed in the second layer 156b by etching such that each pressure chamber 165 communicates, at its one end, with the manifold 169. Further, communicating holes 168, 170 are formed in the second and third layers, respectively by etching such that each pressure chamber 165 communicates, at its other end, with the associated nozzle formed in the nozzle plate 157 through the associated communicating holes 168, 170. The manifold 169, pressure chambers 165, communicating holes 167, 168, 170, and nozzles 158 define ink passages.
The first and second layers 156a, 156b of the cavity plate 156 are as thin as about 20–80 μm and 20–120 μm, respectively. Thus, the cavity plate 156 is likely to bend or buckle when handled for manufacturing the ink-jet head 150, and the manufacturing yield is reduced. To solve such a problem, an ink-jet head 160 having a cavity plate formed by a first layer 166a and a second layer 166b, as shown in FIG. 14, is conceivable. The first layer 166a is made of a single material and formed to a predetermined thickness by unitarily combining the first and second layers 156a, 156b of the cavity plate 156 of FIG. 13. The second layer 166b corresponds to the third layer 156c of FIG. 13. In this case, the first layer 166a undergoes half-etching to form therein pressure chambers 175. Then, the first layer 166a is further etched to form therein communicating holes 177 through which the pressure chambers 175 communicate with a manifold 169 formed in the second layer 166b, and to form therein communicating holes 178 through which the pressure chambers 175 communicate with associated nozzles 158.
In the above-described ink-jet head 160, the pressure chambers 175 are formed in the first layer 166a by half-etching, that is, by etching the first layer 166a halfway in its material thickness. Thus, high precision in depth (in a vertical direction in FIG. 14) is difficult to achieve in the pressure chambers 175. As a result, the pressure chambers 175 have various and uneven depths, and the flow resistance varies among different pressure chambers 175, causing unstable ink ejection therefrom.